[Jac Mac]

No, I was thinking of the OEM sandwich plate ( Approx 0.065" thick ).

It sounds like either a TB problem or the crank end float allowing contact.
If you roll down an incline with motor off, clutch pedal depressed, trans in gear ,does that sound remain or not. If not then its likely a flywheel/clutch cover contact problem , if it remains then its more likely to be TB or plate related.
Many internal TB systems cause problems with larger clutch assy's due to the greater distance they have to move to disengage the clutch. Tilton /QM seem to work best usually on clutches where they may only have to move fingers/diaphragm 3/8" to release. Old rule of thumb is flat brg/radius fingers or vice versa- never flat to flat or round to round, makes the brg tend to wander off center.

Jac Mac